Method and apparatus for a high output sensor system

ABSTRACT

The present invention relates to the field of motion/movement sensors, detectors, and/or monitors, as well as other types of sensors. In particular, the present invention may provide, for example, a large pulsed output voltage in response to very low (or slow) sensed movement or environment changes, such as, temperature, pressure, and energy. The present invention relates, for example, to other available sensors and may provide an output high enough to turn on related processing circuitry from an “OFF” state. The present invention relates, among other things, to sensing various events via, for example, axially poled homopolymer polyvinyladine fluoride (PVDF) or other piezoelectric materials.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation and claims the benefit under35 U.S.C. § 120 of U.S. patent application Ser. No. 10/762,278, filed 23Jan. 2004, now U.S. Pat. No. 7,102,271, which is related to and claimsthe benefit under 35 U.S.C. § 119 of U.S. provisional patent applicationSer. No. 60/536,250, filed 14 Jan. 2004, which are expresslyincorporated fully herein by reference.

FIELD OF THE INVENTION

The present invention relates to the field of motion/movement sensors,detectors, and/or monitors, as well as other types of sensors. Inparticular, the present invention may provide, for example, a largepulsed output voltage in response to very low (or slow) sensed movementor environment changes, such as, temperature, pressure, and energy. Thepresent invention relates, for example, to other available sensors andmay provide an output high enough to turn on related processingcircuitry from an “OFF” state. The present invention relates, amongother things, to sensing various events via, for example, axially poledhomopolymer polyvinyladine fluoride (PVDF) or other piezoelectricmaterials.

BACKGROUND OF THE INVENTION

Presently, there are certain devices available that use piezoelectricactive materials to sense various events. Energy pulses from thesedevices are generally very low in voltage and require the monitoringcircuit to be in an “ON” state, generally incorporating an amplifier toallow the circuit to recognize a sensed event. Previous devices forsensing use a significant amount of continuous energy (quiescentcurrent).

Numerous piezoelectric sensors exist. In general, these sensors fallinto two overlapping categories. They either require an amplifier toboost the signal from the piezoelectric material, or require a biassignal from which the piezoelectric material's signal subtracts or adds.Each of these techniques requires that the sensor be “ON,” drawingcurrent at all times. Thus, a need exists for a sensor that can avoidthe use of an amplifier or a bias signal.

Because a piezoelectric event generally produces only small amounts ofenergy, the detection of low frequency events has previously requiredsignificant amplification. Thus, a need exists for a sensor that candetect low frequency events without the aid of amplification.

SUMMARY OF THE INVENTION

The present invention may relate, for example, to using an unassistedpiezoelectric device as a sensor, monitor or detector. In comparison tothe prior art, the present invention may allow, for example, asignificantly larger voltage pulse to be sent to the monitor circuitry,large enough to be used to switch the entire circuit from an “OFF” stateto an “ON” state, thereby cutting quiescent current usage to extremelylow levels and allowing the use of significantly smaller sensor powersystems. The output of the sensor of the present invention may, forexample, be used to turn “ON” the sensor circuit from an “OFF” state.The present invention may also relate to a sensing device that allowsthe use of non-amplified sensor output signals in a monitoring circuitin the “ON” state, to be recognized when the sensor is in an “OFF”state. This may be accomplished regardless of the polarity of thesignals, and may be accomplished by the beneficial effect of stackingavailable sensor element outputs and using the summed output to turn“ON” a switching device. The switching device may then turn “ON” theentire monitoring circuit.

Sensing can be accomplished with, and is not limited to, positive ornegative changes of the following energy types: thermal; visible light,including infrared or ultraviolet; mechanical motion or impact;triboelectric, including airflow or physical contact; acceleration; andradio frequency (RF) electromagnetic energy, regardless of specificfrequency. The elements of various embodiments of this inventionpotentially include, for example, size of piezoelectric material,mechanical mounting and coupling of piezoelectric material, energytranslation into useful pulses at required voltage levels, regulation(voltage or current), and filtering (if necessary), each of which may,for example, be tuned to fit or combine with required outputs in anyspecific event to be sensed.

There may be significant advantages to stacking low frequency or lowvoltage sensor outputs. For example, stacking low frequency or lowvoltage sensor outputs allows the use of local sensor events (positiveor negative) that were previously not of sufficient charge value orvoltage levels to be useable in even the lowest voltage circuitrywithout amplification.

Another advantage of the present invention may be that the presentinvention may be adapted to operate when supplied with relatively smallamounts of energy. An example energy source for this invention includeslongitudinal stretch motion relative to the object on which anembodiment of the present invention may be mounted. This stretch maysupply energy for longitudinal movements as small as 1.5 μm.Furthermore, in applications based on temperature change, the chargestacking characteristic of the present invention may output pulses basedon a relatively small temperature change. In a stacked element array,the temperature change may be the same for all elements. For example, ina five-element stack, a 0.2° Celsius (one fifth degree) change mayproduce an approximate 8 volt open circuit output pulse. Thus, in an “n”element stack, a 1/n Celsius change may produce an 8 volt open circuitoutput pulse.

An object of an embodiment of the present invention is to provide asensing device that may be optimized for almost any event. It is anotherobject of an embodiment of the present invention to provide a sensingdevice for robotic feeling. The present invention may be useful inrobotic feeling applications because the sensor does not require energyto be expended when there is no sensation present. Additionally, thepresent invention may be capable of detecting very small or lowfrequency events. This detection capability may be useful for robotictactile or other sensors for use in handling delicate or otherwisecomplex situations.

One embodiment of the present invention may be an apparatus for use as asensor including a plurality of stacked piezoelectric elements, arectification block on an output of each of the elements, and aplurality of capacitors arranged to accumulate charge from therectification blocks. Moreover, in certain embodiments, a switchingdevice may be connected to an output of the plurality of capacitors.Although the invention is described in terms of the use of capacitors,the invention may, for example, be implemented by other circuitcomponents that have inherent capacitance. Thus, any element that has auseful capacitance may be considered a capacitive element.

In a particular embodiment of the present invention, the rectificationblock may be a full-wave rectification block or a half-waverectification block. The apparatus may include two or more stackedpiezoelectric elements. Moreover, in a further embodiment of the presentinvention, the apparatus may further include a signal phase delayelement (such as, for example, an inductor) provided between therectification blocks and the capacitors. In another particularembodiment of the present invention, the switch device may comprise atransistor or group of transistors.

The apparatus may be optimized to detect, monitor and/or sense changesin position of an item or structure upon which it is mounted. A door orwindow may be examples of such structures. Should the door or window bemoved even slightly, the sensor of an embodiment of the presentinvention may provide an output. An appropriate angle to mount anembodiment of the present invention to the surface of the item orstructure being monitored may be approximately perpendicular orapproximately 90 degrees to the plane of movement to be monitored.

The apparatus of an embodiment of the present invention may be optimizedfor detecting, monitoring and/or sensing changes in position of an itemor structure that it is placed upon it. Any item or structure that isplaced upon the sensor of an embodiment of the present invention mayprovide a preload of the device that will be changed if the item orstructure is moved from the initial position. An example of such an itemto be monitored is a museum antiquity. If the antiquity is moved, thesensor may provide a desired output. The sensor of this embodiment ofthe present invention may also be configured to avoid certain forms ofdetection. For example, devices that constantly draw current may emitundesired electromagnetic radiation. This electromagnetic radiation canbe “seen” by a variety of sensors. However, certain embodiments of thepresent invention may avoid such detection by not drawing any current(or drawing mere nanoamps) in an untriggered state, thus makingdetection less likely.

An embodiment of the present invention may also be optimized fordetecting changes in position from gravitational effects on a structurerotating at an angle to the surface of a significant gravity source. Awheel is an example of a structure that may be the target for detectionof changes in position by an embodiment of the present invention. Anappropriate angle to the surface for this embodiment may beapproximately perpendicular, or approximately 90 degrees. Such an anglemay provide the maximum amount of change in position in relation to thegravity plane. In general, if other angles are used, the usefulcomponent for measuring may be the component perpendicular to thesurface of the gravity source. Significant gravity sources may includethe earth, the moon, an asteroid, or other bodies significantly largerthan the target.

The apparatus of an embodiment of the present invention may also beoptimized to measure or detect changes in frequency or amplitude from ahuman or other animal heartbeat. The apparatus may alternatively beoptimized for changes in energy available and/or detectable from localelectrical fields. In another embodiment, the apparatus of the presentinvention may be optimized to detect, sense, or monitor changes infrequency or amplitude available from low power sound or ultrasoundenergy. In yet another embodiment, an apparatus of the present inventionmay be optimized for detecting, sensing, or monitoring changes infrequency or amplitude available from RF spectrum energy fields. Inanother embodiment, the apparatus of the present invention may beoptimized to monitor, detect or sense changes in magnetic fields.Additionally, the apparatus may be optimized to monitor, detect or sensevery low frequency energy, down to, for example, the limit of anyparticular piezoelectric material. This limit for DT-1 type materialfrom Measurement Specialties Incorporated, for example, is believed tobe approximately 0.001 Hz.

In certain embodiments of the present invention, the apparatus mayincorporate circuit board technology. For example, the rectificationblocks may be implemented in a circuit board. In such an embodiment, thedevice's capacitive, resistive (if any), or inductive elements may bepart of the circuit board or traces upon the circuit board, rather thandiscrete components. Additionally, inductors may be incorporated incertain embodiments. These may be particularly useful in adjusting thephase of the energy from each element in the stack and may aid inpreventing the output of one element from canceling a portion of theoutput from another element.

Another embodiment of the present invention may include a method ofmanufacturing a sensor including, for example, the steps of arranging aplurality of piezoelectric elements into a stack, connecting arectification block on an output of each of the elements, and arranginga plurality of capacitors to accumulate charge from the rectificationblocks. A further embodiment of the present invention may include, forexample, the step of connecting a switching device to an output of theplurality of capacitors. In a particular embodiment of the presentinvention, the step of arranging may include providing said plurality ofpiezoelectric elements arranged in a stack according to size.

It is understood that both the foregoing general description and thefollowing detailed description are exemplary and explanatory only andare not restrictive of the invention as claimed. The accompanyingdrawings illustrating an embodiment of the invention together with thedescription serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a five-element stack within anembodiment of the present invention.

FIGS. 2A and 2B are schematic diagrams of FET Ground Switchingembodiments of the present invention.

FIGS. 3A, 3B, and 3C are schematic diagrams of FET Power Switchingembodiments of the present invention.

FIGS. 4A and 4B are schematic diagrams of Relay Power Switchingembodiments of the invention.

FIGS. 5A and 5B are examples of motion/movement sensing embodiments ofthe invention including a sensor mounted on an object to sense movement.

FIG. 6 is a drawing of an example of motion/movement sensing by anembodiment of the invention including a sensor placed below an object tosense movement of the object in relation to the sensor.

FIGS. 7A, 7B, and 7C are a mechanical drawing of a five-element stack,one type of physical PVDF layout of and embodiment of the presentinvention.

FIGS. 8A and 8B are layouts depicting a charge device of an embodimentof the present invention optimized for sensing positional change mountedon a wheel at 90° to the surface of the earth or other significant mass(planets, moons, asteroids, etc.).

FIG. 9 is a diagram of sine wave type energy stacking of an embodimentof the present invention.

FIG. 10 is a schematic diagram of a five-element stack, with an optionalsignal phase delay element, such as an inductor, for example, in anotherembodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

It is to be understood that the present invention is not limited to theparticular methodology, compounds, materials, manufacturing techniques,uses, and applications, described herein, as these may vary. It is alsoto be understood that the terminology used herein is used for thepurpose of describing particular embodiments only, and is not intendedto limit the scope of the present invention. It must be noted that asused herein and in the appended claims, the singular forms “a,” “an,”and “the” include the plural reference unless the context clearlydictates otherwise. Thus, for example, a reference to “an element” is areference to one or more elements and includes equivalents thereof knownto those skilled in the art. Similarly, for another example, a referenceto “a step” or “a means” is a reference to one or more steps or meansand may include sub-steps and subservient means. All conjunctions usedare to be understood in the most inclusive sense possible. Thus, theword “or” should be understood as having the definition of a logical“or” rather than that of a logical “exclusive or” unless the contextclearly necessitates otherwise. Structures described herein are to beunderstood also to refer to functional equivalents of such structures.Language that may be construed to express approximation should be sounderstood unless the context clearly dictates otherwise.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meanings as commonly understood by one of ordinary skillin the art to which this invention belongs. Preferred methods,techniques, devices, and materials are described, although any methods,techniques, devices, or materials similar or equivalent to thosedescribed herein may be used in the practice or testing of the presentinvention. Structures described herein are to be understood also torefer to functional equivalents of such structures. All references citedherein are incorporated by reference herein in their entirety.

As described in this specification, applied force is shown as being inthe same general direction and magnitude to each element. The type offorce is immaterial to this explanation and thus a generic force vectorwill be used. Cases involving a different force applied versus film areaor changes in force direction may readily be inferred from this case byan ordinarily skilled artisan. Small variables due to discrete componentcharacteristics are not shown as specific component values because theycan vary; and further because, although this may optimize performance,it does not affect primary performance.

In general, force applied to a PVDF film may cause longitudinal motionof at least a portion of the film. This longitudinal displacement of aportion of the film can generate a voltage output. The magnitude of thevoltage output depends, for example, on the force applied, the physicaldimension of the PVDF film, and the capacitance of the film. The PVDFfilm may be coated with a conductive surface to remove Coulombs ofcharge. In another embodiment, the PVDF film may be in contact with aconductor to remove charge. This process may be reversible, thus, forexample, voltage applied to a conductively coated PVDF film surface maycause physical motion in the film. In axially poled PVDF, most of suchvoltage induced movement may be in the longitudinal direction. Typicallyonly about 1/1000 of the movement will be in any other direction. PVDFfilm that may be used in accordance with the present invention may besuch film as DT-1 film from Measurement Specialties Incorporated.

FIG. 1 is a circuit diagram of an embodiment of the present invention.The diagram illustrates one way in which five piezoelectric elements 150may be electrically connected together. Although the piezoelectricelements 150 are similar to each other, they are not identical. Thesegments of piezoelectric material 130 may be of increasing size and thecapacitors 140 may be selected to correspond to the particular segmentof piezoelectric material 130. An example of such an arrangement isdescribed in FIGS. 7A, 7B, and 7C, which is further described below.Referring again to FIG. 1, each piezoelectric element 150 may include abridge rectifier 120. The bridge rectifier 120 may, for example, be afull-wave rectifier including four diodes 110. The bridge rectifier 120may be connected to the piezoelectric material 130, and may be connectedto a capacitor 140. A stacked array of piezoelectric elements 150 may beconnected electrically by connecting their capacitors 140 in series. Oneterminal of one of the capacitors 140 may be provided as a sensor output170, and another may be connected to ground 160. It may be observed thata four element stack may be created by removing the connection betweenthe bottommost piezoelectric element 150 and instead connecting directlyto ground.

FIGS. 2A and 2B provide two examples of ground switching applications ofthe present invention: a single pulse diagram in FIG. 2A, and a latchedpower diagram in FIG. 2B. In one embodiment, as shown, for example, inFIG. 2A, the sensor output 170 may be connected to the gate of an NChannel FET 210. The source of the N Channel FET 210 may be connected toground 160. The drain of the N Channel FET 210 may be connected tomonitor circuit ground 240. A battery 220 may provide a voltagedifferential between monitor circuit power 230 and ground 160. Thus, asensor high pulse from the sensor output 170 may apply the monitorcircuit ground for the pulse duration.

In another embodiment, as shown, for example, in FIG. 2B, the sensoroutput 170 may be connected to the gate of an N Channel FET 210. Thesource of the N Channel FET 210 may be connected to ground 160. Thedrain of the N Channel FET 210 may be connected to monitor circuitground 240. A battery 220 may provide a voltage differential betweenmonitor circuit power 230 and ground 160. Additionally, a monitorcircuit power latch 250 may be connected through a diode 110 to the gateof the N Channel FET 210. Thus, the high pulse from sensor output 170may indirectly activate the monitor circuit power latch 250, enablingthe circuit to latch power beyond the duration of the pulse.

FIGS. 3A, 3B, and 3C provide three examples of power switchingapplication of the present invention: a single pulse diagram in FIG. 3A,an active-high power latching diagram in FIG. 3B, and an active-lowdiagram in FIG. 3C. In one embodiment, as shown, for example, in FIG.3A, the sensor output 170 may be connected to the gate of an N ChannelFET 210. The source of the N Channel FET 210 may be connected to ground160. The drain of the N Channel FET 210 may be connected to a resistor310 and the gate of a P Channel FET 320. The resistor 310 may beconnected to the source of the P Channel FET 320. The source of the PChannel FET 320 may also be connected to a battery 220 which may, inturn, be connected to ground 160. The drain of the P Channel FET 320 maybe connected to monitor circuit power 230. Thus, a sensor high pulse mayapply monitor circuit power 230 for the pulse duration.

In another embodiment, as shown, for example, in FIG. 3B, the sensoroutput 170 may be connected to the gate of an N Channel FET 210. Thesource of the N Channel FET 210 may be connected to ground 160. Thedrain of the N Channel FET 210 may be connected to a resistor 310 andthe gate of a P Channel FET 320. The resistor 310 may be connected tothe source of the P Channel FET 320. The source of the P Channel FET 320may also be connected to a battery 220 which may, in turn, be connectedto ground 160. The drain of the P Channel FET 320 may be connected tomonitor circuit power 230. Thus, a sensor high pulse may apply monitorcircuit power 230 for the pulse duration. Additionally, a monitorcircuit power latch 250 may be connected through a diode 110 to the gateof the N Channel FET 210. Thus, the high pulse from sensor output 170may indirectly activate the monitor circuit power latch 250, enablingthe circuit to latch power beyond the duration of the pulse.

In another embodiment, as shown, for example, in FIG. 3C, the sensoroutput 170 may be connected to the gate of an N Channel FET 210. Thesource of the N Channel FET 210 may be connected to ground 160. Thedrain of the N Channel FET 210 may be connected to a resistor 310 andthe gate of a P Channel FET 320. The resistor 310 may be connected tothe source of the P Channel FET 320. The source of the P Channel FET 320may also be connected to a battery 220 which may, in turn, be connectedto ground 160. The drain of the P Channel FET 320 may be connected tomonitor circuit power 230. Thus, a sensor high pulse may apply monitorcircuit power 230 for the pulse duration. Additionally, a monitorcircuit power latch 250 may be connected to the gate of the P ChannelFET 320. Thus, the high pulse from sensor output 170 may indirectlyactivate the monitor circuit power latch 250, enabling the circuit tolatch power beyond the duration of the pulse.

FIGS. 4A and 4B provide two examples of relay power switchingapplications of the present invention: a single pulse diagram in FIG.4A, and a latched power diagram in FIG. 4B. In one embodiment, as shown,for example, in FIG. 4A, a sensor output 170 may be attached to a relay410 at pin one. A resistor 310 may be connected between the relay 410 atpin two and ground 160. A battery 220 may be connected between the relay410 at pin three and ground 160. The relay 410 at pin five may remainopen. The relay 410 at pin four may be connected to monitor circuitpower 230. Thus, a sensor high pulse may apply the monitor circuit powerfor the pulse duration.

In another embodiment, as shown, for example, in FIG. 4B, a sensoroutput 170 may be attached to a relay 410 at pin one. A resistor 310 maybe connected between the relay 410 at pin two and ground 160. A battery220 may be connected between the relay 410 at pin three and ground 160.The relay 410 at pin five may remain open. The relay 410 at pin four maybe connected to monitor circuit power 230. Additionally, a monitorcircuit power latch 250 may be connected via a diode 110 to the relay410 at pin one. Thus, a sensor high pulse may apply the monitor circuitpower for the pulse duration. Thus, the high pulse from sensor output170 may indirectly activate the monitor circuit power latch 250,enabling the circuit to latch power beyond the duration of the pulse.

FIGS. 5A and 5B provide two examples of motion sensing with the sensormounted on the object of interest: a window example in FIG. 5A and adoor example in FIG. 5B. In one embodiment, as shown, for example, inFIG. 5A, the sensor 510 may be mounted on a portion of the window 520.In one embodiment, the sensor 510 may be disguised as a sticker that isadvertising a security company. In another example, the sensor 510 maybe placed on an opaque portion of the window 520.

In another embodiment, as shown, for example, in FIG. 5B, a sensor 510may be placed on a door 530. The sensor 510 may, for example, beattached by means of an adhesive. The sensor 510 may be placed on aportion of the door 530 that is particularly likely to move in the eventthat there is an attempt made to open or shut the door 530.

FIG. 6 is an example of a sensor 510 that is pre-loaded by being placedbeneath an object of interest: in this case, a diamond 610. The sensor510 may initially be placed on the surface of, for example, a pedestal620. In this embodiment, if the diamond 610 is lifted from the pedestal620, the sensor 510 will provide an output.

FIGS. 7A, 7B, and 7C are drawings of a five-element stack. FIG. 7Acorresponds to a top view of a five-element stack. FIG. 7B correspondsto a bottom view of a five-element stack. Finally, FIG. 7C shows theapplication of force though a force application center 720 in view thatsuperimposes top and bottom views. This embodiment, for example,converts ambient mechanical energy. A single PVDF film may be sectionedinto five segments of increasing lengths as shown. These segments (orelements) 711, 712, 713, 714, and 715 (which may correspond toparticular segments of piezoelectric material 130 in FIG. 1) may beordered from smallest to largest as depicted. Elements may be created indifferent sizes to provide specifically higher voltages as the film sizeincreases for an evenly applied force across the PVDF film. This permitsthe stack to obtain a positive charge from top to bottom (for example,from the sensor output 170 to ground 160 in circuit diagram, FIG. 1).Capacitors 140 (as shown in FIG. 1) may preferably be matched in size tothe specific capacitance value of the PVDF element with which they arepaired. They may be paired via rectification bridges—shown as 120 in thecircuit diagram. These rectification bridges 120 (as shown in FIG. 1)may preferably be full-wave rectification bridges, but may alternativelybe half-wave bridges. One advantage of full-wave bridges may be theability to capture energy of both polarities. Such a matched pairing maypermit maximum charge transfer from the film. Essentially, the chargetransfer may preferably allow the maximum voltage generated on the PVDFfilm, minus two diode forward voltage drops, to be collected on theassociated capacitor.

A preferred rectification block, for use with the present invention, isa full wave rectifier as this allows voltages lower in the stack toappear on both surfaces of elements higher in the stack. Thisconfiguration may also help, for example, in preventing or diminishingthe effect of individual segments of piezoelectric material 130 that mayconvert applied voltage on one side to mechanical motion within the filmin a direction contrary to applied force.

Force may be applied to the film of an embodiment of the presentinvention roughly perpendicular to the top surface at the center of thefilm, along the force line in the drawing, via an attached mass. For anyapplied force, a voltage may be generated across each piezoelectricelement inversely proportional to the size of the element.

FIGS. 7A, 7B, and 7C are an embodiment of the present invention in whichthe five elements are in a single film. In, for example, rectangularareas, such as the areas for segments 711, 712, 713, 714, and 715, theelements may be defined by the application of silver ink. Care may betaken in the definition of the areas to avert the creation of parasiticcapacitances, by controlling the geometry of the application.

FIGS. 8A and 8B are depictions of an embodiment of the present inventionthat employs a piezoelectric element 150 in a rotational setting. Assuch an embodiment rotates, the gravitational force on the piezoelectricelement 150 changes through 360 degrees of rotation. In a situation inwhich gravitational attraction is 1 G, the force (in the longitudinaldirection) on the element (due to gravity) will vary between 1 G (asseen in FIG. 8B) and −1 G (as seen in FIG. 8A) over the course of therotation.

FIG. 9 is a graph of voltages output from an embodiment of the presentinvention including a PVDF film and stack capacitors. The voltages, inthis example, are generated by a PVDF film and stored in five stackcapacitors by percentage of total output. This percentage may be basedon the ratio of film element capacitance to total element capacitanceusing the element sizing depicted in, for example, FIGS. 7A-7C. If acircuit such as the one shown in FIG. 1 is employed, the voltages acrossthe individual capacitors 140 may vary as shown in correspondingproportional voltages (931, 932, 933, 934, and 935) depicted aswaveforms. In this example, the proportional voltage 931 of thecapacitor 140 connected to sensor output 170 is 25.7% of the totaloutput voltage 936 (also depicted as a waveform). Similarly, theproportional voltage 935 of the capacitor 140 connected to ground 160 is14.3% of total voltage 936.

FIG. 10 is a circuit diagram of another embodiment of the presentinvention. The diagram illustrates one way in which five piezoelectricelements 150 may be electrically connected together. Although thepiezoelectric elements 150 are similar to each other, they are notnecessarily identical. The segments of piezoelectric material 130 may beof increasing size and the capacitors 140 may be selected to correspondto the particular segment of piezoelectric material 130. An example ofsuch an arrangement is described in FIGS. 7A, 7B, and 7C, describedabove. Referring again to FIG. 10, each piezoelectric element 150 mayinclude a bridge rectifier 120. The bridge rectifier 120 may, forexample, be a full-wave rectifier including four diodes 110. The bridgerectifier 120 may be connected to the piezoelectric material 130, andmay be connected to a capacitor 140. Each piezoelectric element 150 mayalso include a signal phase delay element, such as an inductor 180,provided between each bridge rectifier 120 and said capacitive element.A stack of piezoelectric elements 150 may be connected electrically byconnecting their capacitors 140 in series. One terminal of one of thecapacitors 140 may be provided as a sensor output 170, and another maybe connected to ground 160. It may be observed that a four-element stackmay be created by removing the connection between the bottommostpiezoelectric element 150 and instead connecting directly to ground.

Other embodiments of the invention will be apparent to those skilled inthe art from consideration of the specification and the practice of theinvention disclosed herein. It is intended that the specification andexamples be considered as exemplary only, with a true scope and spiritof the invention being indicated by the following claims.

1. An apparatus for use as a sensor comprising a plurality ofpiezoelectric elements, each of said piezoelectric elements having anoutput; a rectification block on each output of said piezoelectricelements; a capacitive element connected to each rectification block toaccumulate charge from said rectification block; a sensor outputconnected to said capacitive elements to supply a signal from saidcapacitive elements, wherein a portion of said charge accumulated bysaid capacitive elements generates a signal that operates a switchingdevice from an “off” state to an “on” state; and a signal phase delayelement provided between said rectification block and said capacitiveelement.
 2. The apparatus of claim 1, wherein said switching device isselected from the group consisting of at least one field effecttransistors (FETs), at least one bipolar transistor, at least one relay,at least one microelectromechanical systems (MEMS) relay, at least onetimer circuit, at least one ferroelectric capacitor, and at least onemicro-controller input.
 3. The apparatus of claim 1, wherein saidrectification block is selected from a group consisting of a full-waverectification block and a half-wave rectification block.
 4. Theapparatus of claim 1 further comprising three or more stackedpiezoelectric elements.
 5. The apparatus of claim 1, wherein said signalphase delay element comprises an inductor.
 6. The apparatus of claim 1,wherein said apparatus comprises a means for detecting changes inposition from gravitational effects on a structure rotating at an angleto the surface of a significant gravity source.
 7. The apparatus ofclaim 1, wherein said apparatus comprises means for detecting changes inposition from movement of a structure the apparatus is mounted upon. 8.The apparatus of claim 1, wherein said apparatus comprises means fordetecting changes in movement of a structure placed upon the apparatus.9. The apparatus of claim 1, wherein said apparatus comprises means fordetecting changes in frequency or amplitude from the group consisting oflow power sound energy, ultrasound energy, and a local electrical field.10. The apparatus of claim 9 wherein said electrical field comprises afield in the approximate range of 50 to 60 Hz.
 11. The apparatus ofclaim 1, wherein one or more of said rectification blocks comprises acircuit board.
 12. The apparatus of claim 1, wherein said apparatuscomprises means for detecting changes in ambient power available from RFspectrum energy fields.
 13. The apparatus of claim 1, wherein saidapparatus comprises means for detecting changes in magnetic fields. 14.An apparatus for use as a sensor comprising a plurality of piezoelectricelements, each of said piezoelectric elements having an output; arectification block coupled with said output of said piezoelectricelements; a capacitive element connected to each rectification block toaccumulate charge from said rectification block; a sensor outputconnected to said capacitive elements and a switching device to supply asignal from said capacitive elements to said switching device withenough power to operate the switching device from an “off” state to an“on” state; and a signal phase delay element provided between saidrectification block and said capacitive element.
 15. The apparatus ofclaim 14, wherein said switching device is selected from the groupconsisting of at least one field effect transistors (FETs), at least onebipolar transistor, at least one relay, at least onemicroelectromechanical systems (MEMS) relay, at least one timer circuit,at least one ferroelectric capacitor, and at least one micro-controllerinput.
 16. The apparatus of claim 14, wherein said rectification blockis selected from a group consisting of a full-wave rectification blockand a half-wave rectification block.
 17. The apparatus of claim 14further comprising three or more stacked piezoelectric elements.
 18. Theapparatus of claim 14, wherein said signal phase delay element comprisesan inductor.
 19. The apparatus of claim 14, wherein said apparatuscomprises a means for detecting changes in position from gravitationaleffects on a structure rotating at an angle to the surface of asignificant gravity source.
 20. The apparatus of claim 14, wherein saidapparatus comprises means for detecting changes in position frommovement of a structure the apparatus is mounted upon.
 21. The apparatusof claim 14, wherein said apparatus comprises means for detectingchanges in movement of a structure placed upon the apparatus.
 22. Theapparatus of claim 14, wherein said apparatus comprises means fordetecting changes in frequency or amplitude from the group consisting oflow power sound energy, ultrasound energy, and a local electrical field.23. The apparatus of claim 22 wherein said electrical field comprises afield in the approximate range of 50 to 60 Hz.
 24. The apparatus ofclaim 14, wherein one or more of said rectification blocks comprises acircuit board.
 25. The apparatus of claim 14, wherein said apparatuscomprises means for detecting changes in ambient power available from RFspectrum energy fields.
 26. The apparatus of claim 14, wherein saidapparatus comprises means for detecting changes in magnetic fields. 27.An apparatus for use as a sensor comprising a plurality of piezoelectricelements, each of said piezoelectric elements having an output; arectification block coupled with said output of said piezoelectricelements; a capacitive element connected to each rectification block toaccumulate charge from said rectification block; a switching devicecoupled with said capacitive element and an electrical device, saidelectrical device having a state; a sensor output connected to saidcapacitive element that supplies a signal from said capacitive elementto said switching device that changes the state of said electricaldevice; and a signal phase delay element provided between saidrectification block and said capacitive element.
 28. The apparatus ofclaim 27, wherein said state is selected from the group consisting of“on” and “off”.
 29. The apparatus of claim 27, wherein said switchingdevice is selected from the group consisting of at least one fieldeffect transistors (FETs), at least one bipolar transistor, at least onerelay, at least one microelectromechanical systems (MEMS) relay, atleast one timer circuit, at least one ferroelectric capacitor, and atleast one micro-controller input.
 30. The apparatus of claim 27, whereinsaid rectification block is selected from a group consisting of afull-wave rectification block and a half-wave rectification block. 31.The apparatus of claim 27, further comprising three or more stackedpiezoelectric elements.
 32. The apparatus of claim 27 wherein saidsignal phase delay element comprises an inductor.
 33. The apparatus ofclaim 27, wherein said apparatus comprises a means for detecting changesin position from gravitational effects on a structure rotating at anangle to the surface of a significant gravity source.
 34. The apparatusof claim 27, wherein said apparatus comprises means for detectingchanges in position from movement of a structure the apparatus ismounted upon.
 35. The apparatus of claim 27, wherein said apparatuscomprises means for detecting changes in movement of a structure placedupon the apparatus.
 36. The apparatus of claim 27, wherein saidapparatus comprises means for detecting changes in frequency oramplitude from the group consisting of low power sound energy,ultrasound energy, and a local electrical field.
 37. The apparatus ofclaim 36 wherein said electrical field comprises a field in theapproximate range of 50 to 60 Hz.
 38. The apparatus of claim 27, whereinone or more of said rectification blocks comprises a circuit board. 39.The apparatus of claim 27, wherein said apparatus comprises means fordetecting changes in ambient power available from RF spectrum energyfields.
 40. The apparatus of claim 27, wherein said apparatus comprisesmeans for detecting changes in magnetic fields.
 41. An apparatus for useas a sensor comprising a plurality of piezoelectric elements, each ofsaid piezoelectric elements having an output; a rectification block oneach output of said piezoelectric elements; a capacitive elementconnected to each of said rectification blocks to accumulate charge fromsaid rectification block; a signal phase delay element provided betweensaid rectification block and said capacitive element; and a sensoroutput connected to said capacitive element to supply a signal from saidcapacitive element, wherein said signal is capable of switching a devicefrom an “off” state to an “on” state.
 42. The apparatus of claim 1,wherein said capacitive elements are connected in series.
 43. Theapparatus of claim 14, wherein the capacitive elements are connected inseries.
 44. The apparatus of claim 27, wherein the capacitive elementsare connected in series.
 45. The apparatus of claim 41, wherein thecapacitive elements are connected in series.
 46. The apparatus of claim1, wherein the piezoelectric elements form a stack.
 47. The apparatus ofclaim 46, wherein at least two of the piezoelectric elements havedifferent respective sizes.
 48. The apparatus of claim 47, wherein thecapacitance of each of the capacitive elements connected to therectification blocks on the outputs of the different sized piezoelectricelements corresponds with the respective size of the piezoelectricelements.
 49. The apparatus of claim 14, wherein the piezoelectricelements form a stack.
 50. The apparatus of claim 49, wherein at leasttwo of the piezoelectric elements have different respective sizes. 51.The apparatus of claim 50, wherein the capacitance of each of thecapacitive elements connected to the rectification blocks on the outputsof the different sized piezoelectric elements corresponds with therespective size of the piezoelectric elements.
 52. The apparatus ofclaim 27, wherein the piezoelectric elements form a stack.
 53. Theapparatus of claim 52, wherein at least two of the piezoelectricelements have different respective sizes.
 54. The apparatus of claim 53,wherein the capacitance of each of the capacitive elements connected tothe rectification blocks on the outputs of the different sizedpiezoelectric elements corresponds with the respective size of thepiezoelectric elements.
 55. The apparatus of claim 41, wherein thepiezoelectric elements form a stack.
 56. The apparatus of claim 55,wherein at least two of the piezoelectric elements have differentrespective sizes.
 57. The apparatus of claim 56, wherein the capacitanceof each of the capacitive elements connected to the rectification blockson the outputs of the different sized piezoelectric elements correspondswith the respective size of the piezoelectric elements.